The present invention relates to a method for conductivity calculation in a treatment fluid upstream and downstream a filtration unit in apparatuses for the blood treatment.
The invention also relates to a method for clearance and fistula flow determination using the above process for conductivity calculation.
It is known in the art to use conductivity measures for determination of parameters indicative of the filter efficiency during treatment, i.e. clearance or dialysance, and for determination of patient parameters, such as fistula flow.
EP 547025 shows a first method for determining clearance starting from a perturbation of the conductivity of the upstream dialysis liquid which creates corresponding response in the conductivity of the liquid downstream the dialysis unit.
Measures of the conductivity allow determination of downstream response and calculation of the clearance.
It is also known from EP 658352 an alternative method to calculate conductivity values for clearance calculation a short time perturbation.
It is also known to determine fistula flow by making a step like perturbation in the upstream conductivity and reversing the lines in the extracorporeal circuit during the step perturbation.
Measuring the conductivities in the spent dialysate across the flow reversal it is possible to arrive at fistula flow determination.